The invention is concerned with fluid-operated pinch valve/regulators. Such devices in general are known to the art and are disclosed, for example, in Craft U.S. Pat. No. 3,468,342 and in Goof U.S. Pat. No. 4,071,039.
The present invention provides a pinch valve/regulator which includes a resilient swell tube closed at one end. The swell tube responds to a pressurized fluid to inflate, and it responds to a spring-biased lever within the unit to deflate when the pressurized fluid is removed. The swell tube causes a planar member in the unit to move in one direction when it inflates, and the spring-biased lever moves the planar member in its opposite direction when the swell tube deflates. The planar member is coupled through the spring-biased lever to a pinch lever which, in turn, performs a pinching function on a fluid-carrying resilient tube within the unit. The fluid-carrying tube is interposed between a pinch bar in the device and one end of the pinch lever.
A feature of the device of the invention is that it incorporates compound levers that provide an enhanced pinching action by the mechanism in an extremely small space. Specifically, the levers provide a mechanical advantage, so that the displacement of the planar member within the device produces a relatively high pinching force against the resilient fluid-carrying tube.
In general, an objective of the present invention is to provide a miniature pinch valve/regulator which is operated by a swell tube in response to the introduction of pressurized fluid. The result is an inherently simple pinch valve/regulator, which does not require pistons, diaphragms, O-rings, or the like in order to achieve its intended purpose.
Another objective of the invention is to provide such a pinch valve/regulator in which there is no interference between the pressurized control pilot fluid flowing into the swell tube, and the controlled fluid flowing through the fluid-carrying tube which is selectively pinched by the device. This obviates the possibility of cross-contamination between the actuating fluid and the controlled fluids in the event of failure of one of the tubes.
Another objective is to provide such an improved valve/regulator which may be manufactured in an expeditious and efficient manner with a low failure rate.
Another objective of the invention is to provide a miniature pinch valve/regulator which may be easily reconfigured at the factory or by the user by repositioning the tubes in the device, or by adding additional tubes and/or tee fittings to enable the device to perform a wide variety of valving and regulating functions.
A further objective of the invention is to provide an improved valve/regulator device which is inherent resistent to clogging.
Yet another objective of the invention is to provide an improved valve/regulator device which may be adjusted significantly to extend its useful life without disassembling the device and without the need for servicing tools, this being achieved by the ease with which the internal pinch tubes of the device may be repositioned.
Another objective of the invention is to provide an improved valve/regulator device which may be sealed to insure against leakage of fluids from the device to the external environment in the event of failure of its pinch tubes, and conversely to inhibit the entry of environmental contaminants or pressurized fluids into the housing of the device.
A more specific objective of the invention is to provide an improved device which in one embodiment to be described offers extremely fine flow control and enables the fluid flow to be turned off with no fluid being retracted into the outlet of the device and with no emission of fluid through the outlet after the device has been shut off.
Yet another objective of the invention is to provide such an improved valve/regulator which is relatively simple to install and service.